It is well known to those skilled in the art that gelled water soluble polymers are useful in enhanced oil recovery operations. A gellable composition comprising a polymer solution is often injected into reservoir rocks and subsequently crosslinked in order to block pore spaces, fractures and other void spaces for the purpose of altering fluid flow to or from the wellbore. Injection of a crosslinked polymer mass into the reservoir subjects the gel structure to mechanical forces that can result in complete degradation of the gel. In order to protect the integrity and quality of the gel, crosslinking of the polymer is normally delayed so that the gel structure is formed in-situ, under low shear or static conditions. At temperatures above 80.degree. C., obtaining a delay in the gellation normally requires the use of organic crosslinkers (e.g. phenol-formaldehyde, furfuryl alcohol-formaldehyde, etc.). Unfortunately, these delays are often too long, and result in extended shut-in periods for the well. The shut-in period results in a loss in production and revenue. In order to minimize the required shut-in times, it is necessary to reduce gel times to just a few hours or days.